Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.

Although the Fresnel lens was invented in 1822, it was not used in the U. S. until the 1850s due to the parsimonious administrator of the United States lighthouse establishment, Stephen Pleasonton.

Although a Dutch spectacle maker created the compound lens and inserted it in a microscope around the turn of the seventeenth century, and Galileo had applied the principle of the compound lens to the making of his microscope patented in 1609, its possibilities as a microscope had remained unexploited for half a century, until Robert Hooke improved the instrument.

Although named after Dutch astronomer Willebrord Snellius ( 1580 – 1626 ), the law was first accurately described by the Arab scientist Ibn Sahl at Baghdad court, when in 984 he used the law to derive lens shapes that focus light with no geometric aberrations in the manuscript On Burning Mirrors and Lenses ( 984 ).

Although all the above lens types — sclerals, PMMA lenses and RGPs — could be correctly referred to as being " hard " or " rigid ", the term hard is now used to refer to the original PMMA lenses, which are still occasionally fitted and worn, whereas rigid is a generic term that can be used for all these lens types: hard lenses ( PMMA lenses ) are a sub-set of rigid lenses.

Although many brands of contact lenses are lightly tinted to make them easier to handle, cosmetic lenses worn to change the color of the eye are far less common, accounting for only 3 % of contact lens fits in 2004.

Although the materials are the same, the manufacturing processes by which the respective contact lenses are made is what differentiates a " daily disposable " lens from a lens recommended for two-week or 4-week replacement.

Although they have less flexibility than monorail cameras, modern field cameras tend to have most camera movements for the front standard, i. e. lens rise / fall / shift / tilt / swing, but are usually more limited in back movements, sometimes having only tilt / swing.

Although many cameras of the mid nineteenth century were wooden and " boxy " in appearance with a brass fitted lens on the front they should not be confused with the mass produced box cameras that exploded in popularity after the introduction of the first Kodak.

Although the lenses appear similar in layout, there is a lot more to the design and performance of a lens than simply the layout of the glass elements.

Although this means that it is not possible to focus the beams nearly as tightly as for light, it also means that the aperture or " capture area " of even the simplest, omni-directional antenna is greatly larger than that of a lens in any feasible optical system.

Although the camera was capable of ' capturing ' motion, it wasn't a complete success because each lens photographed the subject from a slightly different viewpoint and thus the projected image jumped about.

Although the optical format size bears no relationship to any physical parameter of the sensor, its use means that a lens that would have been used with ( say ) a four thirds inch camera tube will give roughly the same angle of view when used with a solid state sensor with an optical format of four thirds inch.

Although Frazier reshot the footage in question with the FrazierPanavision lens the patent was declared unenforceable for inequitable conduct and attorney's fees were awarded to the defendants.

Although the Nikon F3AF ( 1983 ), Pentax ME F and Chinon CE-5 already had presented autofocus single lens reflex cameras, autofocusing could not be achieved without the use of special motorised AF lenses.

Although eye-cups can usually be folded down to allow the spectacle wearer to get closer to binocular eyepieces, there are sometimes lens mountings that do not allow the theoretical eye relief to be obtained.

Although slower, this lens introduced improvements such as optical image stabilisation, a higher zoom range ( 6 ×), and a macro mode that would focus as close as 1 cm.

Although there is no clear beginning or end of a microlensing event, by convention the event is said to last while the angular separation between the source and lens is less than.

Although distortion can be irregular or follow many patterns, the most commonly encountered distortions are radially symmetric, or approximately so, arising from the symmetry of a photographic lens.

Although Night Man has no other superhuman powers on his own, he owns a special bulletproof bodysuit that gives him several abilities, including flight, holographic camouflage-style invisibility and advanced sight functions through the round red lens over his left eye including the ability to see in the dark and fire a laser beam.

Although it is constantly made to look foolish ( too simple to come in out of the rain, people say, who have found in the innocent an impediment ), it does not mind looking foolish because it is not concerned with how it looks.

Although he questions the extent and nature of the alleged revival of religion and the alleged increase in conformity, and thinks that `` hedonistic '' present-time orientation does not have the meaning usually attributed to it, he does conclude that Americans increasingly enjoy leisure without guilt, do not stress achievement so much as formerly, are more accepting of group harmony as a goal, more tolerant of diversity and aware of other cultures.

Although it does not follow the metrical rules for a blues to be sung, the phrases themselves carry a blues feeling.

Although the play does show a certain structural amateurishness ( there are eleven acts varying in length from twenty-five seconds to an hour and a half ), the statement it makes concerning the ceaseless yearning and searching of youth is profound and worthy of our attention.

Although this technique is simple and satisfactory, one practical difficulty does exist: the direction of true north must be known for each launch point.

Although Brooklyn College does not yet have a junior-year-abroad program, a good number of students spend summers in Europe.

Although the titan Rhea does present Dionysus with an amethyst stone to preserve the wine-drinker's sanity in historical text.

Although when burned, amber does give off a characteristic " pinewood " fragrance, modern products, such as perfume, do not normally use actual amber.

Although the terms adiabatic and isocaloric can often be interchanged, adiabatic processes may be considered a subset of isocaloric processes ; the remaining complement subset of isocaloric processes being processes where net heat transfer does not diverge regionally such as in an idealized case with mediums of infinite thermal conductivity or non-existent thermal capacity.

Although Ajax speaks earnestly and is well received, he does not succeed in convincing Achilles.

Although Asser never mentions Alfred's law code, he does say that Alfred insisted that his judges be literate, so that they could apply themselves " to the pursuit of wisdom.

Although it does not match the German exactly, Wheen's title has justly become part of the English language and is retained here with gratitude.

The Court ruled, " Although an Alford plea allows a defendant to plead guilty amid assertions of innocence, it does not require a court to accept those assertions.

Although his name does not appear in any other part of the Jewish Bible, Rabbinic tradition holds Habakkuk to be the Shunammite woman's son, who was restored to life by Elisha in 2 Kings 4: 16.

Although a dormant company, dormancy does not preclude a company actively operating as a nominee shareholder.

Although there is no proof, the name " Thomas Corbett " does appear on the list of dead and missing.

Although in 2002 the NYSE and the NASDAQ required that nominating committees consist of independent directors as a condition of listing, nomination committees have historically received input from management in their selections even when the CEO does not have a position on the board.

Although prepared for an armed conflict with Nigeria in recent years, the Cameroon Army does not have operational experience against other forces, therefore, it is not possible to assess its ability to respond to changing threats and opposing tactics.

Although technology does not exist currently to measure this, it can be estimated by determining oxygen consumption by the brain.

Although Confucius the man may have been a believer in Chinese folk religion, Confucianism as an ideology is humanistic and non-theistic, and does not involve a belief in the supernatural or in a personal god.

Although the Apocrypha was part of the 1611 edition of the KJV, the LDS Church does not currently use the Apocrypha as part of its canon.

Although story events are not triggered by the passage of time, it does determine when merchants rotate their stock.

Although a recognition of sainthood by the Pope does not directly concern a fact of divine revelation, it must still be " definitively held " by the faithful as infallible under ( at the very least ) the Universal Magisterium of the Church since it is a truth connected to revelation by historical necessity.

Although CITES is legally binding on the Parties, it does not take the place of national laws.